Original 1st printing (Maron Lithograph credit) 15&1/4 x 23&1/4" concert poster for Quicksilver Messenger Service appearing with Van Morrison, Clear Light and Blue Cheer at the Earl Warren Showgrounds in Santa Barbara, CA on 9/30/1967.

 Artist unknown/not credited, medium flat vellum stock poster is in mint/near mint to near mint (A/A- to A-) condition; a very clean/sharp example of this brightly-colored image from the Jim Salzer series; check out a great informative list of 1960's-era shows (including this one) held at the Earl Warren Showgrounds:

http://earlwarrenshowgroundsetal.blogspot.com/2010/09/earl-warren-showgrounds.html